Obagi's Nu-Derm system is designed to treat a variety of skin complaints, such as wrinkles, roughness, age spots, discoloration and poor elasticity. The Nu-Derm system comes with cleanser, toner, moisturizer and a product called Blender. When used daily, Blender may have a lightening effect on dark patches or discolored skin.

Obagi's Nu-Derm Blender contains 4 percent hydroquinone for correcting skin discoloration. Hydroquinone lightens skin by slowing down the production of melanosomes in skin pigment cells. It also blocks tyrosinase, an enzyme the body needs to make melanin. This product contains more hydroquinone than over-the-counter creams, so a doctor's or dermatologist's prescription is required for purchase. The Nu-Derm Blender isn't available to buy in physician's offices in some states, including New York, Texas, New Hampshire, Montana and Massachusetts. This is due to state regulations that disallow prescription hydroquinone products to be sold in doctor's offices.

The Nu-Derm Blender product is meant for use as part of an evening routine before bed. Wash your face with the included foaming gel or cleanser, then dab skin with toner. If you have the Nu-Derm Clear product, smooth it over your entire face. Next, apply one or two pea-sized drops of Blender to your entire face. Work the product up to your hairline and over your ears. Finish with a small amount of Nu-Derm Hydrate.

Don't apply this product near your eyes, mouth or nostrils. Hydroquinone may cause mild side effects, including redness, stinging or itching. The product contains sodium metabisulfite, which may cause allergic reactions in some people. After applying, limit sun exposure to avoid re-pigmentation. Consult your doctor before using the product if you're nursing or pregnant. Avoid using hydrogen peroxide or benzoyl peroxide with this product -- doing so can cause a temporary staining of the skin.